The invention relates generally to boring bars and associated measuring gages for accurately positioning a cutting tool on the boring bar. In particular, the invention relates to such a boring bar having a measuring gage attachable thereto.
Various devices have been proposed for use in accurately positioning a cutting tool on a boring bar in order to machine an accurate hole or bore in a workpiece. Some of such devices have necessitated the boring of a trial bore and measuring the size of the bore in order to determine whether the cutting tool is correctly positioned on the boring bar or whether further adjustment is required. Such devices have proved to be cumbersome, time-consuming and wasteful of materials since the position of the cutting tool could not be accurately determined prior to installation of the boring bar assembly on the boring machine.
Various other devices have been proposed for presetting of the cutting tool prior to installing the boring bar on the boring machine or thereafter. Many of such devices have included either generally V-shaped or Y-shaped structures engagable with a cylindrical portion of the boring bar and adapted to support a measuring device during measurement and presetting of the cutting tool. Other of such devices require a special gaging surface on the cutting tool, thereby precluding the use of standard cutting tools which are so commonly used in the machine industry. Such prior devices have typically proved to be inaccurate, difficult to use, time-consuming and inordinately expensive.
It is therefore one of the objects of the present invention to provide a measuring gage device for presetting the radial position of the cutting tip of a cutting tool relative to the rotational center line of a boring bar without introducing the inaccuracies or complications of the prior devices and without requiring a special gaging surface on each individual cutting tool. As used herein, the term "radial" refers to a direction or a position along an imaginary line extending from the rotational center line of the boring bar toward or through its periphery.
In accordance with the present invention, an improved measuring gage device is provided for a boring bar having a cutting tool releasably secured to the boring bar for rotation therewith. The cutting tool is secured to the boring bar so that its cutting tip lies in a reference plane which contains, and is defined by, the cutting tip and the rotational center line of the boring bar. The boring bar includes a gaging surface precisely machined thereon and a measuring gage device engageable with the gaging surface on the boring bar for accurately measuring the radial position of the cutting tip relative to the boring bar's rotational center line. The measuring gage device includes a member having a generally planar measuring surface which is moveable into and out of abutment with the cutting tip to determine its radial position. The measuring device also includes a gaging surface which corresponds to the gaging surface on the boring bar and is mutually engageable therewith in order to substantially assure that the plane of the measuring surface is perpendicular to the reference plane, which is defined by the cutting tip and the boring bar's rotational center line. Preferably, the measuring gage device includes attachment apparatus for releasably fixing the measuring device to the boring bar. Such attachment substantially assures that the gaging surfaces of the measuring gage device and the boring bar are properly engaged in order to maintain the proper alignment of the measuring gage device with the boring bar. The measuring gage device according to the present invention thus accomplishes a high degree of accuracy in the radial positioning of the cutting tip by gaging relative to a planar surface on the boring bar itself which is fixed in spatial relation to the rotational center line thereof of the boring bar, thereby effectively gaging said radial position directly from the center line itself.
Additional advantages and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.